Mussel poop, a weapon in the fight against microplastics?

Microplastics are everywhere: in the water, in the intestines of fish, and even in our food. Faced with this ecological threat, scientists are working to find solutions. A way to combat these tiny particles may have just been found, and it’s in mussel poo, as suggested. a study published in the Journal of Hazardous Materials and relayed by the journal Science.

The difficulty lies in the small size of microplastics, which makes it difficult to clean them. However, the common mussel (mytilus edulis), very voracious, ingests these particles alongside other polluting elements, then rejects them in its excrement. It is then much easier to collect these, where these pieces of plastic material are concentrated. As summarized by Penelope Lindeque, ecologist at the Plymouth Marine Laboratoryin England, who conducted the research, the mussels “take out the trash so that we can pick it up”.

Poo to the rescue

Penelope Lindeque and her colleagues first tested the filtering ability of mussels in the laboratory. Shellfish from a farm in Cornwall were placed in a tank filled with water polluted with microplastics. Eventually, the animals managed to consume nearly two-thirds of these particles and excrete them in their droppings.

To find out for sure, the researchers reproduced the experiment in the natural environment of mussels. Nearly 300 representatives of the species were placed in baskets immersed in tanks, near a marina exposed to pollution. Under the container with the molluscs, another system made it possible to collect their excrement, while allowing the cleaned water to pass through.

In this environment, the animals managed to filter nearly 240 microplastic particles per day. According to the scientists, the result could be even better in waters with a higher plastic concentration, with an estimated capacity of 250,000 particles per hour.

Harvest the microplastics is a first step, but what to do next once your arms are full of shellfish droppings? Penelope Lindeque hopes that mussel poop can be converted into biofilm (a thin layer of protective bacteria, found on rocks in water, for example), so that it can be used in a new way.

Unrealistic on a large scale

Let’s not cry victory too quickly, however, because the droppings of these animals are not the magic bullet. “You will need a lot of molds in lots of different places to see a significant impact”, tempers Evan Ward, an environmental physiologist at the University of Connecticut, who did not take part in the research. According to him, it would take two million shellfish on a 24-hour filtering mission to treat the water in a single bay in New Jersey. Suffice to say that these are not the natural living conditions of mussels.

Penelope Lindeque, while optimistic, is keen to point out that the solution is not found in shellfish but in humans. “We need to stop plastic at its source.” It would not be a question of placing the burden on the mussels.